State Police use an armored vehicle during a standoff with a man in the second floor of a house on the corner of Grace Street and Vanderwerken Avenue, center, on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union) less

State Police use an armored vehicle during a standoff with a man in the second floor of a house on the corner of Grace Street and Vanderwerken Avenue, center, on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy ... more

State Police help a downstairs neighbor evacuate during a standoff at at house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union)

State Police help a downstairs neighbor evacuate during a standoff at at house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union)

Saratoga County Sheriff officer runs into position during a standoff at at house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union)

Saratoga County Sheriff officer runs into position during a standoff at at house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union)

A woman whose sister was initially taken hostage, left, reacts to the standoff at a house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times Union) less

A woman whose sister was initially taken hostage, left, reacts to the standoff at a house on the corner of Grace Street and Vanderwerken Avenue on Monday, Sept. 1, 2014, Waterford, N.Y. (Cindy Schultz / Times ... more

Police were locked in a standoff late Monday with a man who holed himself up in a second-floor apartment in this normally sleepy river community.

Scores of heavily armed officers from a number of agencies, including State Police, were keeping an eye on 65 Grace St., and neighboring homes were evacuated.

Details about what sparked the standoff remained unclear.

A spectator at the scene was heard speaking into a cellphone, apparently pleading with the suspect to give himself up.

No shots had been fired and no serious injuries had been reported as of 11 p.m. But by that time there was still no sign of an end to the situation, and negotiations continued late into the night.

An armored State Police vehicle with heavily armed law enforcement personnel was parked outside the apartment and put a spotlight on the second-floor apartment in which the suspect was believed to be hiding.

Dozens of residents watched the scene for hours in disbelief as State Police wearing flak jackets and armed with shotguns stood behind porches and along the street.